Process of making heat insulating bodies



Patented Mar. 21, 1933 UNITED STATES unar/owne ERNEST J. PIEPER,- DILLON r. sivurn, AND CLARENCE c; voe'r, or HADDONEIELD, NEW JERSEY, ASSIGNORS 'ro ARMSTRONG coax company, or rrrrsromn, PENN SYLVANIA, A CORPORATION OF PENNSYLVANIA PROCESS or MAKING HEAT. msunnrnve BODIES N 0 Drawing.

. This invention relates to insulatingbodies and process of making the same and is particularly useful in. the manufacture of boards 5 or slabs of heat insulating material. 7

The heat insulating value of a material depends upon its density and-upon the number of small air cells which it contains. Many fibrous materials, such as mineral wool, cellulose fibres ancl the like have been used for making insulating bodies-,but it has been necessary toadd a bindingmaterial so a'sto' fecting evaporation of the solvent or solvents.

During the evaporation of the solvent or,

solvents, the binder is carried toward the surface of the body so that the product has a strong and hard exterior shell while the interior remains soft, light and full of minute aircells. The shell may act as a water or fire retarding coating. The insulating body thus formed has the double advantage'of being a good insulating material because of its internal structure, and of possessing long life because of the resistant qualities of its exterior surface; v

Generally stated, the process of manufac ture comprises adding to the body material a solution of a suitable binder in such concentration that while the solvent is being evaporated, the binding material comes to the surface to a greater or less degree. This results in the formation of a hard exterior coating on the softer interionof the board. The thickness of the coating and its density may be regulated at will by controlling the temperature at which the material is dried,

the concentration of the solution of binder Application filed October 10, 1927. Serial No. 225,390.

and the kind of solvent or mixture of solvents in which. the binder is dissolved,

The invention is p'arti'cularly useful in. making boards or slabs of insulating'material, the non uniform distribution of the binderin the mass of body material resulting in the formation of'a board having hard-and dense sides and edges and a soft core of high H made of any deslred slze and for house msu- 1 insulating properties. Such. boards may be lating maybe nailed to the' framing in' the condition they are received from the factory.

A pecific illustration of our method 01- lows:

"Ten gallons ofa 20% solution of asphalt innaptha was placed inasuitable'mixer and to this was added two and one-half pounds of mineral wool. The mineral wool wasthor oughlymixed in the solution; The excess solution was removedin a suction mold and. the body thus formed in the moldwas taken therefrom] and dried at a temperature sufliv I cient'to volatilize the 3 mm: The excess solution removed in the suction mold may be returned to thefmixer and used for thetreatment of further quantities ofmineral wool; The. relativedensityflof the shell and the center of the board may be varied. Quick drying gives a board with a very porous and fiufiy center while slow dryingcauses a more uniform final distribution of'the binder. In either, case, however, the board has a relatively hard shell and soft center.

Inthe above recited example, the distribution of the binder in the mass is indicated by the relative color of the shell and the center, If the board is quickly dried, the shell is dark and the center is very light in color, thus showing that practically all of the asphalt is used as a solvent. .Where the solvent is naptha and kerosene or kerosene alone, the

col or distribution is more uniform.

Body materials other than mineral wool ticularly useful. These may either be inorganic fibres, such as mineral wool or asbestos, or organic fibres. Other solvents and binders may be used. The following are examples of binders and solvents which have been found satisfactory:

(a) Nitrocellulose lacquer-amyl acetate as chief solvent (7)) Varnishalcohol or turpentine as chief solvent v a k (0) ax tailingsnaptha assolv'ent (d) Stearine pitch-naptha as solvent .;The"fiber is generally mixed with an;excessof solution.This is desirable as it insures thorough mixing. The excess solution may be removed in the mold or by means of a centrifuge or other means. For continuous production of insulating board a machine of the Fourdrinier type may be 'used 'and the excess, solvent taken off when. the mixis on the w1re.1 The excess solvent thereforemay be removed either before or during'the mold ing step.

- Theinvention perniits 'of making insulat ing bodies at a low. labor cost and lpermit's of using relatively inexpensive materials. a @We havedescribed a preferred embodimentof the invention'and certainmodifications thereof, "I It" will be understo'odphowever',1that.it is not limited to the materials'or tothe sequence of steps described, as it may be ;otherwise embodied or practiced. within the scope of the following claims.

.1. The process of making bonded heat insulating bodies having greater. concentration of binder at the surface than at the interior, which comprises forming a body of. insulate ing material impregnated with aibinder in solution in a volatile, solvent, and evaporate ing the solvent from the body, the solvent being initially present ,in sufficient amount and the rate, of evaporation beingsufliciently rapid todraw a part, at least, of the binder fromthe interior toward the su rface. y 1. 2. Theprocess of makingbondedheat insulating bodies having unequal distribution of binder therein, which comprises forming a body of insulating material impregnated with a binder in solution. avolatile solvent, and evaporating the solvent fromthe body at the portion thereof where it is de sired to have the greater concentration-of binder, thesolvent being initially present in sufficient amount and the rate of evaporation being, sutficiently rapid to draw apart, at least, of the ,binderfrom the'other portions of the body towardsuch portion.

.-3.:The process of making bonded heat insulating bodies which comprises mixing heat body with sufficient rapidity to draw the dissolved binder from the interior to the surface, whereby the body is formed with a relatively open porous'interior and a relatively hard dense surface.

4. The process of making bonded heat insulating bodies, which comprises mixing a body material with a binder in liquid solution in a volatile solvent andshaping the mass to form the body, and applying heat to effect a suiiiciently rapid evaporation of the solvent to transfer a considerable portion of the dissolved binder from the center to the tively hard dense exterior.

v 5. The process of making bonded heat insulatingbodies, whichcomprises forming a mix containing a fibrous material 7 and a binder dissolved in a volatile solvent and molding the article from such mix, and thereafter evaporating the solvent from the molded body, the solvent beinginitially present in sufiicie'nt amount and the rateof evaporationbeing sutficiently rapid to draw enough of thcdissolved binder from the interior to the surface ofithe body to produce a relatively open porous interiorand a relatively hard dense surface. g L V 6. The, process of making bonded heat insulating bodies, which comprises forming a body containing a fibrous material and a binder in solution in. a volatile solvent distributed therein, and evaporating thejsolvent from the bodyJthe' solvent being! initially present in sufficientamountfand the rate of evaporation being sufficiently rapidto transfer a considerable portion of the dissolved binder from the interior .of the body 'tojits surface and deposit such transferred binder at the surface so as .to produce a surface layer considerably. morecompact and dense than, the materialat the'interior of the body.

7 The process of making a heat insulating unit,wl1ich compriseslmixing mineralfibers with a binder inliquid solution in .a

set ourhandsf I ERNESTJLPIEPER,

' a DILLON' F. SMITH. i

CLARENCE C. VOGT=1 insulating material -with a binder in liquid I solution in a, relatively large amount of a Y volatile solvent and shaping the bodythere- 

